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JP-10 is a potential endothermic hydrocarbon fuel (EHF) with a high energy density for the regenerative cooling technology of advanced aircrafts. In this work, pyrolysis and coking of JP-10 were experimentally studied using an electrically heated tube as a flowing reactor under supercritical conditions (4.5 MPa, 550–735 °C). For the supercritical pyrolysis, dicyclopentadiene, exo-TCD4e, and indane/indene were observed with relatively higher selectivity at low conversion, and the selectivities of typical products (ethene, propene, CPD, cyclopentene, and benzene) were lower compared with that under atmospheric pressure, possibly because of the enhanced bimolecular reactions. The heat sink of JP-10 was approximately 2.5 MJ/kg ascribed to the severe coke formation during the pyrolysis. Further characterizations on cokes indicated that the coke in the bulk fluid was about 70–170 times higher than that deposited on the wall, attributed to rapid formation of polycyclic aromatic hydrocarbons (PAHs) of pyrolysis products rather than the wall catalysis.

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The chemical heat sink of endothermic hydrocarbon fuels (EHFs) is generally dependent on its thermal cracking in the cooling channel, which is accompanied and limited by the formation of carbon deposit. In this work, HF-1 (a kerosene-based EHF) was electrically heated in the rectangular, square, and circular channels with the same cross-sectional area under 3.5 MPa to study the effect of cooling channel geometric structures on the thermal cracking and carbon deposition behaviors. It was found that under similar conditions (inlet flow rate of fuel, pressure, outlet temperature), conversions of HF-1 in both rectangular and square channels were slightly higher than that in the circular one with high selectivity to methane but lower selectivities to the primary cracking products (such as 1-hexene and 1-heptene, etc.). In addition, more carbon deposits were formed in the rectangular and square channels, especially around the corners of channels. Based on the CFD simulation, the possible reasons should be ascribed to the difference in the gradient uniformity near the wall of different channels. The higher temperature and lower velocity in the boundary layer of the quadratic channels might cause the thermal cracking to be slightly severer and the rapid secondary reactions to form carbon deposit.

High-pressure thermal decomposition of tetrahydrotricyclopentadiene (THTCPD) and binary high-density hydrocarbon fuels of JP-10/THTCPD were investigated at 500−660 °C and 4.0 MPa in an electrically heated tubular reactor. The decomposition of THTCPD under high temperature, high pressure, and low residence time was conducted to analyze their effects on the products. The experimental results of JP-10/THTCPD pyrolysis show that the THTCPD pyrolysis is greatly easier than the thermal cracking of JP-10, and the addition of JP-10 can significantly promote the THTCPD pyrolysis, which is evidenced by the fact that THTCPD conversion increases up to 80% at 660 °C when blended with 50% JP-10. It may be ascribed to possible reason about the pathway and mechanism of JP-10/THTCPD pyrolysis is that the free radicals generated by the decomposition of THTCPD help to promote the decomposition of JP-10 via H-abstraction reactions. Correspondingly, a large number of new free radicals generated from the JP-10 pyrolysis could also react with JP-10 and THTCPD, which is helpful to promote the decomposition of THTCPD via H-abstraction reaction. Besides, the contribution of THTCPD to JP-10 could also explained by the chemical equilibrium point of view, since JP-10 is one of the products of THTCPD. Meanwhile, the thermal isomerization pathways of THTCPD are also slightly changed in the presence of JP-10. Our experiments could provide necessary information for the potential applications of THTCPD fuels in advanced aircraft.

Tetracyclo[6,2,1,01,7,13,6]dodecene (TCD) is conventionally synthesized by continuous heating of norbornene (NBE) and dicyclopentadiene (DCPD), in which the synthesis rate and isomer selectivity are hardly improved under such near equilibrium conditions. In this study, an alternative thermochemical synthesis technique using direct electric heating is present. Alternate heating and cooling of the reaction mixture can be rapidly realized by programmable electric current flowing in the reactor tube. The reaction has been switched in a timely fashion between high temperature and low temperature at a given speed. At a high temperature, the active intermediate of cyclopentadiene (CPD) quickly forms. Rapid cooling ensures the nonequilibrium kinetic control of CPD copolymerization for increasing the selectivity. The energy cost is reduced by lowering the average temperature. As optimized by the Bayesian method, the operating conditions of oscillating heating (e.g., amplitude, frequency, pressure, and so on) are determined to precisely match the time scales of fast generation and directed consumption of CPD. The oscillating heating method leads to a high yield of endo,exo-TCD (62.4% versus 11.6% by the conventional continuous-heating method). High-energy-density fuels with good low-temperature fluidity are prepared using hydrogenated TCD as the key component.

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